Bottom Line:
On the other hand, expression of the G2/M transition activator CYCB1 was substantially induced in elp2.The auxin efflux transporters PIN1 and PIN2 showed decreased protein levels and PIN1 also displayed mild polarity alterations in elp2, which resulted in a reduced auxin content in the root tip.Either the acetylation or methylation level of each of these genes differed between the mutant and the wild type, suggesting that the ELP2 regulation of root development involves the epigenetic modification of a range of transcription factors and other developmental regulators.

Figure 2: The foreshortening of the roots produced by the elp2 mutant reflects a reduced level of cell proliferation and cell elongation. (A) Roots of 12-day-old seedlings of WT and elp2. (B) Primary root growth of WT and elp2 seedlings 4 d post germination. The data represent the mean and SD (n=40) derived from at least three independent experiments. (C) Variation in root meristem cell number of five-day-old WT and elp2 seedlings. Cell numbers counted from the QC to the TZ. The data represent the mean and SD (n=20) derived from at least three independent experiments. (D) Representative five-day-old WT and elp2 seedlings illustrating that the latter develop a reduced MZ and EZ. (E) Five-day-old WT and elp2 seedlings. The cortex TZ is indicated by white arrowheads. (F) Epidermal cell length of the DZ in six-day-old WT and elp2 seedlings. Bars, 50µm (E, F). **, P<0.001 (This figure is available in colour at JXB online.)

Mentions:
In addition to the root stem cell niche identity defect, the elp2 mutant also produced shorter roots than the WT seedlings (Fig. 2A, B, Supplementary Fig. S4). This shortening was a result of smaller elongation (EZ) and meristem (MZ) zones (Fig. 2D, E). Cell number in the MZ and cell length in the EZ were both reduced compared to the WT (Fig. 2C, F), suggesting that ELP2 affects both cell proliferation and cell elongation.

Figure 2: The foreshortening of the roots produced by the elp2 mutant reflects a reduced level of cell proliferation and cell elongation. (A) Roots of 12-day-old seedlings of WT and elp2. (B) Primary root growth of WT and elp2 seedlings 4 d post germination. The data represent the mean and SD (n=40) derived from at least three independent experiments. (C) Variation in root meristem cell number of five-day-old WT and elp2 seedlings. Cell numbers counted from the QC to the TZ. The data represent the mean and SD (n=20) derived from at least three independent experiments. (D) Representative five-day-old WT and elp2 seedlings illustrating that the latter develop a reduced MZ and EZ. (E) Five-day-old WT and elp2 seedlings. The cortex TZ is indicated by white arrowheads. (F) Epidermal cell length of the DZ in six-day-old WT and elp2 seedlings. Bars, 50µm (E, F). **, P<0.001 (This figure is available in colour at JXB online.)

Mentions:
In addition to the root stem cell niche identity defect, the elp2 mutant also produced shorter roots than the WT seedlings (Fig. 2A, B, Supplementary Fig. S4). This shortening was a result of smaller elongation (EZ) and meristem (MZ) zones (Fig. 2D, E). Cell number in the MZ and cell length in the EZ were both reduced compared to the WT (Fig. 2C, F), suggesting that ELP2 affects both cell proliferation and cell elongation.

Bottom Line:
On the other hand, expression of the G2/M transition activator CYCB1 was substantially induced in elp2.The auxin efflux transporters PIN1 and PIN2 showed decreased protein levels and PIN1 also displayed mild polarity alterations in elp2, which resulted in a reduced auxin content in the root tip.Either the acetylation or methylation level of each of these genes differed between the mutant and the wild type, suggesting that the ELP2 regulation of root development involves the epigenetic modification of a range of transcription factors and other developmental regulators.